"Does anyone else straight get the fantasies of this?" Only just about every other straight man in the world. It is perfectly normal for a straight man to have gay dreams and fantasies. Practically all straight men do. Conversely almost all gay men have straight dreams and fantasies.

So the question is, do you want to turn those fantasies into reality? Sooner or later, most straight men do. There are a multitude of reasons for this. Perhaps the most common is that he wants to get his own cock sucked and is willing to suck to get it done. ("I'll suck yours if you suck mine.") Or he could do it to find out what it's like or just to prove to himself that he can. There are probably as many different reasons as there are men in the world.

So if you're comfortable sucking another guy's cock, go for it.